1. Field of the Invention
The present invention generally relates to a boost pressure diagnostic apparatus for an internal combustion engine equipped with a forced induction device. More specifically, the present invention relates a boost pressure diagnostic apparatus that determines if a boost pressure is abnormal in an internal combustion engine equipped with a forced induction device.
2. Background Information
Japanese Laid-Open Patent Application Publication No. 2007-77897, for example, discloses an apparatus comprising a throttle valve, a forced induction device provided on upstream the throttle valve, a bypass valve provided in a passage arranged to circumvent the forced induction device, and a boost pressure sensor configured to detect a pressure upstream of the throttle valve. The apparatus is configured to determine that an abnormality exists in the bypass valve when the pressure upstream of the throttle valve is larger than a preset pressure determination value and has remained larger than the preset pressure determination value continuously for a prescribed amount of time after the bypass valve was opened.